The squacco heron (Ardeola ralloides ) is a small heron, 44–47 cm (17+1⁄2–18+1⁄2 in) long, of which the body is 20–23 cm (8–9 in), with 80–92 cm (31+1⁄2–36 in) wingspan. It is of Old World origins, breeding in southern Europe and the Greater Middle East.
The English common name squacco comes via Francis Willughby (c. 1672) quoting a local Italian name sguacco. The current spelling comes from John Hill in 1752.
The scientific name comes from Latin ardeola, a small heron (ardea ), and ralloides, Latin rallus, a rail and Greek -oides, "resembling".
The squacco heron is a migrant, wintering in Africa. It is rare north of its breeding range. The species has been recorded in Fernando de Noronha islands, and more rarely in mainland South America, as a vagrant. This is a stocky species with a short neck, short thick bill and buff-brown back. In summer, adults have long neck feathers. Its appearance is transformed in flight, when it looks very white due to the colour of the wings.
The squacco heron's breeding habitat is marshy wetlands in warm countries. The birds nest in small colonies, often with other wading birds, usually on platforms of sticks in trees or shrubs. Three to four eggs are laid. They feed on fish, frogs and insects.
Northern populations in Europe and west Asia are migratory. Southward migration is August–November, and appears to occur at a rather leisurely pace. Birds move in a broad front across Europe, the Middle East and the Sahara. Return migration is in February and March to as late as May. Migration appears to be along a broad front in that migrating birds are seen widely throughout the Mediterranean and its islands. Migration in both seasons crosses the Sahara.
Widespread post-breeding dispersal of juveniles begins in July continuing until migration. Spring migration leads to frequent overshoots. So, outlying dispersal records are common. Dispersal records include Iceland, Britain (Moon 1997, Greason 1998), Belgium, Luxembourg, Netherlands, Denmark, Germany, Sweden, Finland, Austria, Poland, west central Asia, Azores, Madeira, the Canary and Cape Verde Islands, and Brazil (Fernando de Noronha island) (Nacinovic and Teixeira 1989). In the Indian Ocean, there are dispersal records from the Comores and Mauritus, undoubtedly from Madagascar.
No comments:
Post a Comment